On a transmission network provided by a network operator, a single user-specific, e.g., private, connection or a user-specific or private network can be created for a user. The user of the connection or network provides the network operator with the necessary configuration data. On the basis of data provided by the future user, which is typically in the form of verbal requirements profiles, the network operator creates the connection or network as a network service, so to speak. For this purpose, use is made, for example, of a network management system for managing, controlling, and monitoring the transmission network. The configuration data specify, for instance, the access points to the transmission network between which the connection or network is to be created. The configuration data may also include information about the desired availability, i.e., the fail-safety, of the connection or network.
To guarantee a desired availability, the network operator will, for instance, create so-called protected connections, that provide additional spare or protective transmission capacity that is available in the event of a failure of the normal capacity of the connection. The provision of spare transmission capacity is complicated and entails additional costs for the user.
To achieve a predetermined availability, it is also possible to build a user-specific or private ring network on the basis of a transmission network. In such a private ring network, each node of the transmission network is connected to two adjacent nodes. However, the exclusive assignment of network nodes to the ring network is also complicated, and the complexity of its implementation increases with increasing number of connections of the ring network. Furthermore, routing algorithms to be used by user-located network nodes, e.g., by IP routers (IP=Internet Protocol), particularly in case of a fault, are optimized for meshed networks, but not for ring networks. Moreover, large ring networks show a tendency towards instability.
To obtain connections that are as reliable as possible, the user can create connections or have connections created in such a way that from his or her point of view, they are likely to be routed through network devices and over transmission lines of the transmission network which are independent of each other. For instance, the user can select access points for the connections which are far apart. Still, two or more connections of the user-located network may be routed through common devices of the transmission network, for instance through a central network node. In the event of a failure of the common device, all connections routed through the latter will be out of order, so that the necessary reliability of the connections is actually not provided.
It is therefore an object of the invention to permit the creation of at least one user-specific connection, particularly of a user-located network, on a transmission network, particularly taking into account the availability of the transmission network.